A refined analysis of thunderstorm outflow characteristics relevant to the wind loading of structures

Shi, Zhang; Solari, Giovanni; Gaetano, Patrizia De; Burlando, Massimiliano; Repetto, Maria Pia

doi:10.1016/j.probengmech.2017.06.003

Cited by 75 publications

(63 citation statements)

References 46 publications

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“…A 10 min mean wind speed in integer knots and direction in 10 sectors at 0.5 hr intervals from 1973 to 2017 (45 years) was extracted from the NCEI TD3505 database, and the common artefacts described by Cook (2014a) were removed by the automated method of Cook (2014b). This also removed thunderstorm downbursts which are poorly represented by 10 min means (Zhang et al, 2018). After detecting and cleaning the artefacts, 74% of the possible half-hour observations at Fiumicino and 76% at Ciampino survive to contribute to the analysis.…”

Section: Wind Observationsmentioning

confidence: 99%

Parameterizing the seasonal–diurnal wind climate of Rome: Fiumicino and Ciampino

Cook

2019

Meteorological Applications

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This study uses the Offset Elliptical Normal (OEN) mixture model to parameterize the seasonal–diurnal wind climate of Rome, Italy, for engineering design purposes, and also to reveal the physical meteorology of this “mixed” wind climate. The joint probability density function (PDF) of the wind vectors in the zonal–meridional plane are represented by a mixture of disjoint bivariate‐Normal ellipses. Each OEN ellipse is tentatively attributed to a physical wind mechanism: sea/land breezes; transient coastal jets; katabatic flows; the migrating atmospheric tide; and (non‐diurnal) geostrophic winds. The model enables a fuzzy probability of each wind mechanism to be assigned to each observation, allowing the progression of the various diurnal cycles to be tracked through time. This seasonal–diurnal parametric model is directly applicable to wind energy resource estimation, pollution studies, pedestrian comfort, and heating and ventilation design. The model is also an essential starting point in methods to simulate realistic time series of wind speed and direction.

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Section: Wind Observationsmentioning

confidence: 99%

Parameterizing the seasonal–diurnal wind climate of Rome: Fiumicino and Ciampino

Cook

2019

Meteorological Applications

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“…This will yield a wind field that is more turbulent, which means a more conservative structural response. The assumption that the turbulence intensity is height-independent is inline with the work done by Zhang et al (2017).…”

Section: Turbulent Componentmentioning

confidence: 87%

“…The downburst size was chosen to be of average size ). Yet, the downdraft velocity, which is comparable to near-surface velocity, was chosen to be higher than common stationary downburst ground velocities in field that are usually less as reported by Holmes et al (2008), Ponte and Riera (2010), and Zhang et al (2017). The higher velocity was chosen since design analyses are usually conducted on critical values that would cause failures of transmission lines.…”

Section: Mean Componentmentioning

confidence: 99%

The Dynamic Effect of Downburst Winds on the Longitudinal Forces Applied to Transmission Towers

Ibrahim

Damatty

Elawady

2019

Front. Built Environ.

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Electric power transmission line systems are a key component in the development of our modern societies. The uninterrupted availability of electric power mandates building transmission line structures that can withstand severe natural hazards. The current study focuses on the performance of conductor line systems subjected to downburst loading, which along with other types of wind events are responsible for 80% of weather related failures of transmission lines. Due to the special configuration of downburst wind fields, a unique failure mode of transmission line structures can be found to damage the cross-arms of the supporting towers as a result of the development of longitudinal forces in the conductor lines. The main concern of the current study is to explore the dynamic effect of downburst loading on these longitudinal forces, and to examine the validity of using quasi-static analysis. This is done through two levels of analysis, model-scale and full-scale. The model-scale analysis is first used to propose a simulation technique that can predict the dynamic response of conductor systems due to downburst loading overcoming the complexity induced by time varying aerodynamic damping coefficients. The proposed model is validated using a unique experiment conducted at WindEEE dome testing facility at The University of Western Ontario in Canada. The validated model is used to conduct analysis at the full-scale level using a wind field generated by a Computational Fluid Dynamics (CFD) model. Results show that the longitudinal forces within the conductor system are dynamically insensitive and can therefore be treated quasi-statically. Lastly, to judge the applicability of the wind field used, a comparison was made between the CFD wind field and full-scale records. The comparison was done through two parameters that would affect the quasi-static response; the first relating the peak velocity to the post peak velocity, and the second defining the ramping period. It was concluded from the comparison that varying the defined parameters would result in a maximum difference of 5% in the computed reactions.

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“…First, 93 records labelled as thunderstorm outflows were extracted (Solari et al, 2015a). Then, on increasing the available data, 247 non-stationary records were gathered (Zhang et al 2018a). All records were subjected to extensive probabilistic analyses aiming at evaluating their main properties relevant to the wind loading of structures.…”

Section: Wind Speed Analysismentioning

confidence: 99%

Mixed Climatology, Non-synoptic Phenomena and Downburst Wind Loading of Structures

Solari

2019

Lecture Notes in Civil Engineering

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In 1961 Davenport published a paper, considered by most the constitutive deed of Wind Engineering, where meteorology, micrometeorology, climatology, aerodynamics and structural dynamics were embedded into a homogeneous framework of the wind loading of structures. This scheme, known as the "Davenport chain" and referred to a synoptic-scale extra-tropical cyclone is so limpid and elegant as to become a sort of axiom. Between 1976 and 1978 Gomes and Vickery separated thunderstorm from non-thunderstorm winds, determined their extreme distributions and derived a mixed statistical model later extended to other phenomena; this study, a milestone in the emerging issue of mixed climatology, proved the impossibility of labelling a heterogeneous range of phenomena characterized by different velocity fields, frequencies, durations and extensions by the generic term "wind". Many of these phenomena occur in limited and well-known areas. Extra-tropical cyclones and thunderstorms affect the entire planet. This paper provides a state-of-the-art of this subject, with particular regard to the studies conducted at the University of Genova on thunderstorms.

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A refined analysis of thunderstorm outflow characteristics relevant to the wind loading of structures

Cited by 75 publications

References 46 publications

Parameterizing the seasonal–diurnal wind climate of Rome: Fiumicino and Ciampino

Parameterizing the seasonal–diurnal wind climate of Rome: Fiumicino and Ciampino

The Dynamic Effect of Downburst Winds on the Longitudinal Forces Applied to Transmission Towers

Mixed Climatology, Non-synoptic Phenomena and Downburst Wind Loading of Structures

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